Non-Axisymmetric Coriolis Vibratory Gyroscope With Whole Angle, Force Rebalance,

Abstract

This paper presents detailed performance status and projections for the silicon MEMS Quadruple Mass Gyroscope (QMG) -a unique high Q, lumped mass, mode-symmetric Class II Coriolis Vibratory Gyroscope (CVG) with interchangeable whole angle, self-calibration, and force rebalance mechanizations. Analysis of a QMG sealed without getter with a Q-factor of 1e3 reveals an Angle Random Walk (ARW) of 0.02 deg/rt-hr limited only by the fundamental Mechanical-Thermal Noise (MTN). Propagation of a detailed noise model to a QMG sealed with getter at a Q-factor of 1e6 (previously demonstrated) showed better than Navigation Grade ARW of 0.001 deg/rt-hr. Combination of the very low ARW with the mode-symmetry enabled self-calibration substantiates the navigation grade performance capacity of the Si-MEMS QMG.

MEMS and FOG Technologies for Tactical and Navigation Grade Inertial Sensors—Recent Improvements and Comparison

“…With class II gyros such as quad mass gyros, methods for dynamic self-calibration have been proposed [25] and promise a new revolutionary MEMS gyro performance range. However, there are also drawbacks in terms of complexity and redundancy and the alternative is to reserve aging margins in the specification and to monitor key characteristics during the manufacturing process.…”

“…The next true MEMS revolution with a jump in performance over about two orders of magnitude however, is likely to rely on class II quad mass gyroscope designs [25]. …”

Redundant information processing techniques comparison for differential vibratory gyroscope

“…The single requirement is a change of control algorithm of the standing wave vibratory structure. Therefore functioning of differential CVG can be considered as the third mode of CVG operation [12] in addition to two well-known rate-integrating [13] and rate measurement [14].…”

Performance of Quad Mass Gyroscope in the Angular Rate Mode

“…The QMG device described herein has evolved considerably from the first introduction of the concept in [ 18 ], in terms of its structure and control architecture, demonstrating an excellent modal symmetry and exceptional Q-factor. Features of the design discussed here are categorized into three design iterations: (QMG-I) with mass symmetry and an external lever mechanism [ 18 , 26 ], (QMG-II) with mode-ordering, as well as an internal and external levering, comb-finger drive electrodes and parallel-plate sense electrodes [ 27 , 28 ], and, (QMG-III) with a complete symmetry of the design, including internal and external levering, with differential parallel-plate drive and sense electrodes [ 29 , 30 ], and vacuum sealing with getters. Table 1 summarizes the key parameters of these iterations, the performance numbers and the corresponding publications, a visual comparison of the layouts is provided in [ 31 ] Section 3.2.4.…”